Method and apparatus for visualizing a medical instrument under ultrasound guidance

Abstract

Systems and methods of facilitating the viewing of interventional instruments (e.g., needles, catheters, guidewires, vascular filters, biopsy probes) are disclosed herein. In one embodiment, a portable, handheld or cart-based ultrasound imaging machine is connected to an external laser light source that transmits laser light to a tip of an interventional instrument via one or more optical fibers. The laser light is absorbed at the distal tip of the instrument and generates a photoacoustic signal. The ultrasound imaging machine creates an image by combining data from the received photoacoustic signals with ultrasound echo data to show both tissue in a region of interest and the tip of the interventional instrument.

We claim: 
     
       1. A system, comprising:
 a laser light source configured to produce laser light pulses; 
 one or more optical fibers having a first end and a second end, the first end configured to be optically coupled to the laser light source, the second end configured to be attached to an interventional instrument and to produce photoacoustic signals in response to receiving the laser light pulses; 
 a transducer configured to transmit ultrasound signals toward a region in a subject and to receive:
 ultrasound echoes from the subject based on the ultrasound signals; and 
 the photoacoustic signals; and 
 
 an ultrasound machine configured to:
 generate, based on the ultrasound echoes and the photoacoustic signals, an image that depicts an anatomical feature in the region and a representation of the interventional instrument; and 
 synchronize the laser light source with the transducer including to instruct the transducer to generate the ultrasound signals with a reduced energy when the laser light source produces the light pulses. 
 
 
     
     
       2. The system of  claim 1 , wherein the ultrasound machine is configured to synchronize the laser light source with the transducer including to generate trigger signals and transmit the trigger signals to the laser light source, and the laser light source is configured to produce the laser light pulses upon receipt of the trigger signals. 
     
     
       3. The system of  claim 1 , wherein the second end of the one or more optical fibers includes a light absorbing medium configured to produce the photoacoustic signals. 
     
     
       4. The system of  claim 1 , wherein the transducer is configured to generate the ultrasound signals with the reduced energy by reducing an amplitude of the ultrasound signals. 
     
     
       5. The system of  claim 1 , wherein the transducer is configured to generate the ultrasound signals with the reduced energy by reducing a duration of the ultrasound signals. 
     
     
       6. The system of  claim 1 , wherein the ultrasound machine is configured to receive a signal from the laser light source indicating that one or more optical fibers have been inserted into the laser light source and to begin operating in a needle visualization mode responsive to said receive the signal from the laser light source. 
     
     
       7. The system of  claim 1 , wherein the ultrasound signals include ultrasound beams, and said synchronize the laser light source with the transducer includes to interleave the laser light pulses with the ultrasound beams, wherein the ultrasound machine is configured to receive the ultrasound echoes interleaved with the photoacoustic signals. 
     
     
       8. The system of  claim 1 , wherein the ultrasound machine is configured to colorize the anatomical feature and the representation of the interventional instrument separately for the image. 
     
     
       9. The system of  claim 1 , wherein the interventional instrument includes a needle and the second end is positioned adjacent a tip of the needle. 
     
     
       10. The system of  claim 1 , wherein the ultrasound machine is configured to generate a trigger delay to compensate for a time delay between a first time at which a trigger signal is transmitted to the laser light source and a second time at which a laser light pulse is generated by the laser light source in response to the trigger signal to align a photoacoustic image frame associated with the photoacoustic signals with an ultrasound image frame associated with the ultrasound echoes. 
     
     
       11. The system of  claim 1 , wherein the ultrasound machine is configured to determine that an intensity of photoacoustic data associated with the photoacoustic signals is greater than a predetermined threshold to mark the photoacoustic data as corresponding to the interventional instrument. 
     
     
       12. An ultrasound machine, comprising:
 a transducer configured to transmit ultrasound signals toward a region in a subject and to receive ultrasound echoes from the subject based on the ultrasound signals; and 
 a processor configured to:
 combine echo data based on the ultrasound echoes and photoacoustic data based on photoacoustic signals produced responsive to laser light pulses from a laser light source to create an image that shows an anatomical feature in the region and at least a portion of an interventional instrument; 
 generate trigger signals to instruct the laser light source to generate the laser light pulses; and 
 generate control signals to instruct the transducer to reduce an energy of the ultrasound signals transmitted by the transducer to a minimal energy to synchronize the laser light pulses with the ultrasound signals having the minimal energy transmitted by the transducer. 
 
 
     
     
       13. The ultrasound machine of  claim 12 , wherein the transducer is configured to reduce the energy of the ultrasound signals to the minimal energy by reducing an amplitude or a duration of the ultrasound signals in response to the control signals. 
     
     
       14. The ultrasound machine of  claim 12 , wherein the processor is configured to begin operating in an instrument visualization mode upon receipt of a signal from the laser light source that indicates that one or more optical fibers have been connected to the laser light source. 
     
     
       15. The ultrasound machine of  claim 12 , wherein the processor is configured to stop operating in an instrument visualization mode upon receipt of a signal from the laser light source that indicates that one or more optical fibers have been disconnected from the laser light source. 
     
     
       16. The ultrasound machine of  claim 12 , wherein the processor is configured to interleave the laser light pulses with the ultrasound signals on an image frame basis by interleaving an amount of the laser light pulses corresponding to a photoacoustic image frame with an amount of the ultrasound signals corresponding to an ultrasound image frame. 
     
     
       17. A method of operating an ultrasound machine, the method comprising:
 transmitting, with a transducer of the ultrasound machine, ultrasound signals toward a region of a subject; 
 acquiring ultrasound echo data based on ultrasound echoes that are received by the transducer in response to the ultrasound signals transmitted; 
 generating trigger signals to control a laser light source to produce laser light pulses, wherein the laser light pulses are transmitted from a first end of one or more optical fibers that is coupled to the laser light source to a second end of the one or more optical fibers that is coupled to an interventional instrument to produce photoacoustic signals in response to the laser light pulses; 
 generating control signals to synchronize the transducer and the laser light source, the control signals indicating to reduce an energy of the ultrasound signals transmitted by the transducer to a minimal energy when the laser light source produces the laser light pulses; 
 acquiring photoacoustic data from the photoacoustic signals; and 
 combining the ultrasound echo data and the photoacoustic data to produce an image that shows an anatomical feature in the region and at least a portion of the interventional instrument. 
 
     
     
       18. The method of  claim 17 , further comprising:
 transmitting the trigger signals to the laser light source over a wired or wireless communication link. 
 
     
     
       19. The method of  claim 17 , further comprising:
 receiving a signal from the laser light source indicating that the one or more optical fibers have been removed from the laser light source; and 
 automatically halting, upon receipt of the signal from the laser light source, a photoacoustic imaging process that includes said generating the trigger signals. 
 
     
     
       20. The method of  claim 17 , further comprising:
 determining a location of a tip of the interventional instrument based on the photoacoustic signals and not based on the ultrasound echoes.